Standard outbreak metrics like the reproduction number ($R_0$) are mathematically incapable of predicting whether a public health intervention will actually work.
Researchers proved that two epidemics can have identical growth rates and infection counts but respond in opposite ways to the same intervention—one vanishing while the other explodes. This reveals that the indicators used by governments globally to justify lockdowns or vaccine mandates are 'blind' to the underlying structures that determine if a disease can be controlled.
Epidemic indicators do not determine intervention performance
medRxiv · 10.64898/2026.03.27.26349564
Epidemic growth rates, reproduction numbers and counts of new infections are universally used to guide public health intervention decisions. It is widely and reasonably believed that larger values of these indicators evidence the need for more urgent or stringent control. Here we show that this intuition can fail dramatically. We construct pairs of epidemics with indistinguishable growth rates, reproduction numbers and infection curves but fundamentally divergent responses to identical intervent